Rosellichalasins A-H, cytotoxic cytochalasans from the endophytic fungus Rosellinia sp. Glinf021.

Eight new cytochalasans rosellichalasins A-H (1-8), as well as two new shunt metabolites rosellinins A (9) and B (10) before intramolecular Diels-Alder cycloaddition reaction in cytochalasan biosynthesis, along with nine known cytochalsans (11-19) were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata. Their structures were characterized by extensive analysis of 1D and 2D NMR as well as HRESIMS spectra and quantum chemical ECD calculations. The cytotoxic activities of these compounds were evaluated against four human cancer cell lines including HCT116, MDA-MB-231, BGC823, and PANC-1 with IC50 values ranging from 0.5 to 58.2 µM.

Rare cytochalasans isolated from the mangrove endophytic fungus Xylaria arbuscula.

Four new cytochalasans, arbuschalasins A-D (1-4), along with thirteen known analogues (5-17), were isolated from the solid rice medium of endophytic fungus Xylaria arbuscula. Arbuschalasins A-B feature a rare 5/6/6/6 fused ring system while arbuschalasin D was characterized as the first example of natural cytochalasans that possesses a 5/5/11 fused scaffold. The structures of 1-4 were assigned by spectroscopic data, with their absolute structures being determined by electronic circular dichroism (ECD) calculations. All of the isolates were evaluated against the human colorectal adenocarcinoma cell lines (HCT15). Compounds 6 and 7 showed significant inhibitory effects (IC50 values were 13.5 and 13.4 µM, respectively), being more active than those of the positive control, fluorouracil (103.1 µM).

Cytochalasans from endophytic fungus Diaporthe sp. SC-J0138.

Five new cytochalasans, diaporthichalasins D-H (1-5), along with five known cytochalasans (6-10) were isolated from solid cultures of the endophytic fungus Diaporthe sp. SC-J0138 isolated from the leaves of Cyclosorus parasiticus. Their structures were elucidated by analysis of spectroscopic data and theoretical calculations of electronic circular dichroism spectra. Compounds 1 and 5 showed noticeable cytotoxicity against human carcinoma A549, HeLa, and HepG2 cells. The structure-activity relationships in cytotoxicity were discussed for this group of compounds.

Cytotoxic 19,20-epoxycytochalasans from endophytic fungus Xylaria cf. curta.

Nine new 19,20-epoxycytochalasans (1-9) were isolated from the rice fermentation extracts of endophytic fungus Xylaria cf. curta, along with four known compounds 19,20-epoxycytochalasin C (10), 18-desoxy-19,20-epoxycytochalasin C (11), 19,20-epoxycytochalasin D (12) and 5,6-dihydro-7-oxo-19,20-epoxycytochalasin C (13). Their structures and absolute configurations were determined by 1D and 2D NMR, HRESIMS, X-ray diffraction and ECD calculation. The cytotoxicity of obtained compounds (1-13) was evaluated against human cancer cell lines HL-60, A549, SMMC-7721, MCF-7, and SW480. Remarkably, compound 10 showed significant specific cytotoxicity against HL-60 cell lines with IC50 value of 1.11 µM.

Cytotoxic cytochalasans from fungus Xylaria longipes.

Five new cytochalasans (1-5) were isolated from the rice fermentation of fungus Xylaria longipes, along with seven known compounds cytochalasin P (6), cytochalasin D (7), zygosporin D (8), 7-O-acetylcytochalasin D (9), cytochalasin C (10), 6,7-dihydro-7-oxo-cytochalasin C (11), and 6,7-dihydro-7-oxo-deacetylcytochalasin C (12). Their structures and absolute configurations were determined by extensive experimental spectroscopic methods as well as ECD calculation and GIAO 13C NMR calculation. The cytotoxicity of obtained compounds (1-12) was evaluated against human cancer cell lines HL-60, A549, SMMC-7721, MCF-7, and SW480. Compounds 6-8, 11, and 12 showed cytotoxicity with IC50 value ranging from 4.17-37.18 µM.

Cytochalasins and polyketides from the fungus Diaporthe sp. GZU-1021 and their anti-inflammatory activity.

Four new compounds: diaporthichalasins A-C (1-3) and biatriosporin N (7), along with six known compounds (4-6 and 8-10) were separated from the culture of the fungus Diaporthe sp. GZU-1021. The absolute configurations of 1-3 were determined by quantum chemical calculations, X-ray diffraction, and spectroscopic analysis. The structure of 4 was analyzed by X-ray crystallography analysis for the first time. All of the isolates were evaluated on the production of nitric oxide in lipopolysaccharide-induced microglial cells (RAW 264.7 cells). Compounds 5-10 exhibited significant inhibitory effects against nitric oxide production with IC50 values from 1.94 to 16.5 µM than positive control (indomethacin, IC50 = 29.7 µM). This is the first time tetrahydroxanthone dimer (10), as a novel carbon skeleton possessing NO inhibitory activity, was reported.

Cytotoxic seco-cytochalasins from an endophytic Aspergillus sp. harbored in Pinellia ternata tubers.

Six new seco-cytochalasins A-F (1-6), two new asperlactones G-H (7-8) along with three known cytochalasins (9-11) were isolated from the solid cultures of an endophytic fungus Aspergillus sp. Their structures were elucidated by comprehensive spectral analysis, and their absolute configurations were determined through Mo2(OCOCH3)4-induced electronic circular dichroism (ECD) spectra and Rh2(OCOCF3)4-induced ECD experiment. Compounds 5 and 6 were rare seco-cytochalasins possessing an α, ß-unsaturated furanone structure in their side-chains. These isolates exhibited cytotoxicity against human lung cancer A-549 cell line with IC50 values ranging from 7.8 to 70.2 µM. At the concentration of 16 µM, compound 4 also exerted a 3-fold enhancement of doxorubicin susceptibility on doxorubicin-resistant human breast cancer (MCF-7/DOX) cell line.

New cytochalasin from Rosellinia sanctae-cruciana, an endophytic fungus of Albizia lebbeck.

AIM: To explore the potential of Rosellinia sanctae-cruciana an endophytic fungus associated with Albizia lebbeck for pharmaceutically important cytotoxic compounds. METHODS AND RESULTS: One novel cytochalasin, named jammosporin A (1) and four known analogues (2-5) were isolated from the culture of the endophytic fungus R. sanctae-cruciana, harboured from the leaves of the medicinal plant A. lebbeck. Their structures were elucidated by extensive spectroscopic analyses including one-dimensional and two-dimensional nuclear magnetic resonance data along with MS data and by comparison with literature reports. In preliminary screening the ethyl acetate extract of the fungal culture was tested for cytotoxic activity against a panel of four cancer cell lines (MOLT-4, A549, MIA PaCa-2 and MDA-MB-231), and found to be active against MOLT-4 with an IC50 value of 10 µg ml-1 . Owing to the remarkable cytotoxic activity of the extract the isolated compounds (1-5) were evaluated for their cytototoxicity against the MOLT-4 cell line by MTT assay. Interestingly, compounds 1-2, 4 and 5 showed considerable cytotoxic potential against the human leukaemia cancer cell line (MOLT-4) with IC50 values of 20·0, 10·0, 8·0 and 6·0 µmol l-1 , respectively, while compound 3 showed an IC50 value of 25 µmol l-1 . This is the first report of the existence of this class of secondary metabolites in R. sanctae-cruciana fungus. CONCLUSION: This study discovered a novel compound, named jammosporin A, isolated for the first time from R. sanctae-cruciana, an endophytic fungus of A. lebbeck with anticancer activity against the MOLT-4 cell line. SIGNIFICANCE AND IMPACT OF THE STUDY: Rosellinia sanctae-cruciana represents an interesting source of a new compound with bioactive potential as a therapeutic agent against a human leukaemia cancer cell line (MOLT-4).

Cytochalasin E in the lichen Pleurosticta acetabulum. Anti-proliferative activity against human HT-29 colorectal cancer cells and quantitative variability.

A biological screening of sixteen lichen extracts on human HT-29 colorectal cancer cells, led to the selection of Pleurosticta acetabulum, a lichen widely present in tree barks in Europe. Bioguided purification of the acetonic extract resulted in the isolation of cytochalasin E, a common fungal metabolite. This compound is responsible for the anti-proliferative activity of the extract. Its presence in lichens is reported here for the first time. LC-MS quantitation of cytochalasin E in different samples of P. acetabulum demonstrated quantitative variations of cytochalasin E production in the lichen and especially high concentrations in apothecia.

Antibacterial and cytotoxic cytochalasins from the endophytic fungus Phomopsis sp. harbored in Garcinia kola (Heckel) nut.

BACKGROUND: The continuous emergence of multidrug-resistant (MDR) bacteria drastically reduced the efficacy of our antibiotic armory and consequently, increased the frequency of therapeutic failure. The search for bioactive constituents from endophytic fungi against MDR bacteria became a necessity for alternative and promising strategies, and for the development of novel therapeutic solutions. We report here the isolation and structure elucidation of antibacterial and cytotoxic compounds from Phomopsis sp., an endophytic fungus associated with Garcinia kola nuts. METHODS: The fungus Phomopsis sp. was isolated from the nut of Garcinia kola. The crude extract was prepared from mycelium of Phomopsis sp. by maceration in ethyl acetate and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The isolated compounds were evaluated for their antibacterial and anticancer properties by broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide methods respectively. The samples were also tested spectrophotometrically for their hemolytic properties against human red blood cells. RESULTS: The fractionation of the crude extract afforded three known cytochalasins including 18-metoxycytochalasin J (1), cytochalasins H (2) and J (3) together with alternariol (4). The cytochalasin compounds showed different degrees of antibacterial activities against the tested bacterial pathogens. Shigella flexneri was the most sensitive microorganism while Vibrio cholerae SG24 and Vibrio cholerae PC2 were the most resistant. Ampicillin did not show any antibacterial activity against Vibrio cholerae NB2, Vibrio cholerae PC2 and Shigella flexneri at concentrations up to 512 µg/mL, but interestingly, these multi-drug resistant bacterial strains were sensitive to the cytochalasin metabolites. These compounds also showed significant cytotoxic properties against human cancer cells (LC50 = 3.66-35.69 µg/mL) with low toxicity to normal non-cancer cells. CONCLUSION: The three cytochalasin compounds isolated from the Phomopsis sp. crude extract could be a clinically useful alternative for the treatment of cervical cancer and severe infections caused by MDR Shigella and Vibrio cholerae.

Cytochalasin derivatives from a jellyfish-derived fungus Phoma sp.

Four new cytochalasin derivatives (1-4), together with proxiphomin (5), were isolated from a jellyfish-derived fungus Phoma sp. The planar structures and relative stereochemistry were established by analysis of 1D and 2D NMR data. The absolute configuration was defined by the modified Mosher's method. The compounds showed moderate cytotoxicity against a small panel of human solid tumor cell lines (A549, KB, and HCT116).

Cytotoxic cytochalasins from marine-derived fungus Arthrinium arundinis.

Four new cytochalasins, arthriniumnins A-D (1-4), a new natural product, ketocytochalasin (5), as well as five known cytochalasin analogues (6-10) were isolated and identified from the fungus Arthrinium arundinis ZSDS1-F3 from the sponge Phakellia fusca. Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, as well as single crystal X-ray diffraction. Compounds 6 and 9 showed cytotoxicity against K562, A549, Huh-7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.13 to 47.4 µM.

A new cytochalasin from endophytic Phomopsis sp. IFB-E060.

AIM: To study the chemical constituents of the solid culture of the endophyte Phomopsis sp. IFB-E060 in Vatica mangachapoi. METHOD: Isolation and purification were performed through silica gel column chromatography, gel filtration over Sephadex LH-20, ODS column chromatography, and HPLC. Structures of the isolated compounds were elucidated by a combination of spectroscopic analyses (UV, CD, IR, MS, 1D, and 2D NMR). The cytotoxicity of the isolates was evaluated in vitro by the MTT method against the human hepatocarcinoma cell line SMMC-7721. RESULTS: Five compounds were isolated from the solid culture of the endophyte Phomopsis sp. IFB-E060 and their structures were identified as 18-methoxy cytochalasin J (1), cytochalasin H (2), (22E, 24S)-cerevisterol (3), ergosterol (4), and nicotinic acid (5). Compound 1 had an inhibition rate of 24.4% at 10 µg·mL(-1) and 2 had an IC50 value of 15.0 µg·mL(-1), while a positive control 5-fluorouracil had an inhibition rate of 28.7% at 10 µg·mL(-1). CONCLUSION: 18-Methoxy cytochalasin J (1), produced by endophytic Phomopsis sp. IFB-E060, is a new cytochalasin with weak cytotoxicity to the human hepatocarcinoma cell line SMMC-7721.

Stereochemical determination of new cytochalasans from the plant endophytic fungus Trichoderma gamsii.

Three new cytochalasans, trichalasins E (1), F (2) and H (7), together with four known analogues, trichalasin C (3), aspochalasin K (4), trichalasin G (5) and aspergillin PZ (8), were isolated from one endophytic fungus Trichoderma gamsii inhabiting in the traditional medicinal plant Panax notoginseng (BurK.) F.H. Chen. Trichalasins E (1) contains a unique hydroperoxyl group, which is the first report in all known analogues, whereas trichalasin H (7) possesses the rare 6/5/6/6/5 pentacyclic skeleton with 12-oxatricyclo [6.3.1.0(2,7)] moiety as that of aspergillin PZ (8). The relative configurations of the new compounds were characterized by analysis of coupling constants and ROESY correlations, and the absolute configurations of trichalasins E (1), H (7) and aspergillin PZ (8) were determined by modified Mosher's reaction. In addition, compounds 1-5, 7 and 8 were tested cytotoxic activities against several cancer cell lines.

Cytochalasin H, an active anti-angiogenic constituent of the ethanol extract of Gleditsia sinensis thorns.

Angiogenesis, the process of new vessel formation from the pre-existing blood vasculature, is critical for continuous tumor growth and is considered to be a validated antitumor target. The results of our previous study demonstrate the anti-angiogenic potential of an extract of Gleditsia sinensis thorns, which has been traditionally used in Korean medicine to remedy diverse diseases, including tumors. In the present study, we attempted to identify the active anti-angiogenic constituents of the ethanol extract of G. sinensis thorns (EEGS). By virtue of in vitro activity-guided fractionation using human umbilical vein endothelial cells (HUVEC) primary endothelial cells, chromatographic separation, and NMR spectral analyses, we isolated and identified the potent active constituent, cytochalasin H, a biologically active secondary metabolite of fungi. This unexpected active constituent may have originated from the endophytic fungi, Chaetomium globosum, which naturally populate G. sinensis, the identity of which was determined by analysis of fungal community. Cytochalasin H isolated from the EEGS showed in vitro anti-angiogenic activities such as suppressed cell growth and mobility in HUVEC, and inhibited the pro-angiogenic protein-induced formation of new blood vessels in vivo. The anti-angiogenic effect of cytochalasin H was in part due to reduced expression of pro-angiogenic factor, such as endothelin-1. This is the first report regarding the isolation and identification of cytochalasin H, as an active anti-angiogenic constituent of G. sinensis thorns.

Trichalasins C and D from the plant endophytic fungus Trichoderma gamsii.

Two new cytochalasans, trichalasins C (1) and D (2) together with known cytochalasans aspochalasins D (3), M (4) and P (5) were isolated from one endophytic fungus Trichoderma gamsii inhabiting in traditional medicinal plant Panax notoginseng (BurK.) F.H.Chen. The structures for the new compounds 1 and 2 were determined by NMR and HRESIMS, and their relative configurations were established by analysis of coupling constants and NOESY correlations. Compound 3 displaying inhibitory activity with EC50 value 5.72 µM, whereas the EC50 values for compounds 1, 2 and 4, 5 are more than 40 µM.

Metabolites of the mangrove fungus Xylaria sp. BL321 from the South China Sea.

Two new lactones, 1 and 2, together with five known compounds, 3-7, were isolated from the marine mangrove fungus Xylaria sp. BL321. Their structures were determined by comprehensive analysis of their MS and NMR spectroscopic data. The absolute configurations of 1 and 2 were established on the basis of electronic circular dichroism calculations. It was found that the exocyclic double bond of 1 rearranged into a cyclic double bond to form a new crystal compound (1a) in diluted NaOH solution. Compound 3 was isolated for the first time as a natural product; its absolute configuration was determined by single-crystal X-ray crystallography. Compounds 4-7 displayed cytotoxicity against human breast cancer cell lines MCF-7 and MDA-MB-435, while compounds 1- 3 were inactive (IC(50) > 50 µM).

Ardeemins and cytochalasins from Aspergillus terreus residing in Artemisia annua.

Three new alkaloids, 15b-dehydro-5- N-acetylardeemin ( 3), 10-phenyl-[12]-cytochalasins Z16 ( 6) and Z17 ( 7), were characterized from the liquid culture of the endophytic fungus ASPERGILLUS TERREUS IFB-E030 along with six known derivatives, 5- N-acetylardeemin ( 1), 15b- ß-hydroxyl-5- N-acetylardeemin ( 2), cytochalasin E ( 4), rosellichalasin ( 5), cytochalasins Z11 ( 8), and Z13 ( 9). The structures of the new metabolites were established mainly by a combination of their 1D- and 2D-NMR spectra, single crystal X-ray diffraction, and the modified Mosher reaction. Biological assays indicated that cytochalasin Z17 ( 7) had moderate cytotoxicity against human nasopharyngeal epidermoid tumor KB cell line with an IC (50) value of 26.2 µM.

Protoplast mutation and genome shuffling induce the endophytic fungus Tubercularia sp. TF5 to produce new compounds.

Tubercularia sp. TF5 is an endophytic fungal strain isolated from the medicinal plant Taxus mairei. Previously, taxol has been detected in the fermentation products of this strain. However, it lost the capability of producing taxol after long-term laboratory culture. Herein, we tried to reactivate the production of taxol by protoplast mutations and genome shuffling. The protoplasts of Tub. sp. TF5 were prepared from its mycelia, and mutated by UV and NTG. The mutant strains regenerated from the mutated protoplasts were selected and classified into four groups on the basis of their phenotypes, the profile of their metabolites analyzed by TLC, MS, and bioassay data. Then, genome shuffling was subsequently carried out with eight mutant strains, with two representatives from each protoplast mutant group, and genome shuffling mutant strains were obtained and screened using the same screening procedure. Although taxol has not been detected in any mutant, two important mutants, M-741 and G-444 were selected for metabolites isolation and determination due to their phenotypes, and differences in TLC analysis result from TF5 and other mutants. Three new sesquiterpenoids, namely tuberculariols A-C (1-3), and a known dihydroisocoumarin (4) were obtained from M-741. Eighteen novel compounds were isolated from G-444, including five new sesquiterpenoids (5-9), two new dihydroisocoumarins (10, 11), one new tetralone (12), together with 10 known compounds (13-20, 1, and 2). The compounds isolated from the M-741 and G-444 were different in structure types and substitutions from those of TF5 (15, 21-29). The results showed, for the first time, that protoplast mutations and genome shuffling are efficient approaches to mining natural products from endophytic fungi. Understanding the mechanisms of unlocking the biosynthesis of new metabolites will facilitate the manipulation of the secondary metabolism in fungi.

Apoptosis induction in HCT116 cells by cytochalasins isolated from the fungus Daldinia vernicosa.

We examined the induction of apoptosis by cytochalasin (cc) derivatives (1-14) isolated from the Japanese fungus Daldinia vernicosa to HCT116 human colon cancer cell line based on their cytotoxicity, DNA ladder and DNA fragmentation ratio in agarose gel electrophoresis, and morphological changes. Most cc derivatives tested here induced apoptosis. Particularly cytochalasin 1 (cc1), monoacetate of 1 (cc1Ac), and cc14 were the most potent apoptosis inducers. These apoptotic activities were stronger than that of cytochalasin D as a known apoptosis inducer in HCT116 cell. However, cc4 and cc12 induced necrosis. The structure-activity relationship including their cytotoxicity will be discussed.